Structural and Optical Properties of Polymer Blend Nanocomposites Based on Poly (vinyl acetate-co-vinyl alcohol)/ TiO2 Nanoparticles

Abstract

Titanium dioxide and organic polymer blend poly (vinyl acetate-co-vinyl alcohol) based nanocomposite membranes were prepared and their chemical structure, phase relationship and optical properties investigated. The Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) analysis reveals TiO2 to be almost isomorphic (≥99% phase purity) with spherical particles having diameters in the range 25-40 nm. The composites were characterized by Fourier Transform Infrared (FTIR), SEM, X-Ray Diffraction (XRD) and Ultraviolet-visible (UV-vis) Spectrophotometry. The FTIR Spectroscopy reveals significant absorptions below 900 cm-1 to represent Titanium bonds with organic groups and Oxygen while other prominent functional groups above 900 cm-1 reflect the additivity of polyvinyl alcohol and polyvinyl acetate. It was found that embedding inorganic nanoparticles of TiO2 into the polymer blend matrix of poly (vinyl acetate-co-vinyl alcohol) allowed for some crystallinity formation and cross-linking of the polymer composites during annealing. The XRD results show more defined peaks assigned to each phase of the composite as the TiO2 content increases from 1 to 4% weight ratio, thus indicating that Nanoparticle filler remain in the semi-crystalline polymer matrix as a separate crystalline phase, which is in good agreement with the SEM. Finally, the resonant coupling between Ultraviolet-visible (UV-vis) light and the collective electronic transitions of polymer nanocomposites are examined using UV-vis Spectrophotometer. The variation in the percentage absorbance and transmittance over wavelength range 200 nm-900 nm is also attributed to TiO2 Nanoparticles (Nps) content        (1-4%) in the samples.